Comment 3 for bug 1713751

I switched back to the Ubuntu linux-image-4.10.0-33-generic kernel and about 6 reboots later it happened again, so its definitely specific to the Ubuntu kernel. I was able to catch it right as it happened, the last thing before the NMI watchgdog messages occur is:

[ OK ] Reached target Shutdown.

The only errors visible on the screen are [FAILED] unmounting /tmp and /var , I always get the failure unmounting /var but not /tmp, maybe that is significant? I had /tmp on a separate partition, I removed its fstab entry so it will be on the / root partition, we'll see if that changes anything.